| music store? most likely not
qualified luthier? most likely so depending on the specifics of the bass and hardware
to do this correctly, you need a bridge designed to accommodate a string-thru set-up, a drill press for accurately drilling the holes (a 4-step process in my shop), and a bass body style that is suitable for a string-thru mod (i.e. no hollow body, or cavities under the bridge)
depending on the exact scope of the job, it should range from one - three hours of shop time for a disassemble, drill work, installation of ferrules and bridge, reassemble, and intonation/set-up.
that's quite a load of $$$ for next to zero sonic difference ... IMO, of course
all the best,
R | 
